I don't know if this was mentioned as there are large parts of this thread that I just skipped over
, but what is the condition of the pulleys for the a/c system? If the belt had been loose and slipping for a long period of time the "Vee" inside the pulley is worn down and the belt starts to suck into the centre of the pulley. This could cause some interesting vibration problems.
Good to see that you have it worked out, Johann. You have had some very good advice from some of the contributors.
Cheers!